package com.fly.estore.framework.util;

import java.security.MessageDigest;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.UUID;

/**
 * Created by Fly on 2016/3/25.
 */
public class CommonUtil {

    /**
     * 使用UUID生成主键，去掉"-"
     * @return 主键值
     */
    public static String genPK(){
        UUID uuid = UUID.randomUUID();
        return uuid.toString().replaceAll("-", "");
    }


    /**
     * 使用MD5加密字符串
     * @param s 待加密字符串
     * @return  加密后的字符串
     */
    public static String MD5Encode(String s) {
        char hexDigits[]={'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};

        try {
            byte[] btInput = s.getBytes();
            // 获得MD5摘要算法的 MessageDigest 对象
            MessageDigest mdInst = MessageDigest.getInstance("MD5");
            // 使用指定的字节更新摘要
            mdInst.update(btInput);
            // 获得密文
            byte[] md = mdInst.digest();
            // 把密文转换成十六进制的字符串形式
            int j = md.length;
            char str[] = new char[j * 2];
            int k = 0;
            for (int i = 0; i < j; i++) {
                byte byte0 = md[i];
                str[k++] = hexDigits[byte0 >>> 4 & 0xf];
                str[k++] = hexDigits[byte0 & 0xf];
            }
            return new String(str);
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

    public static String dateToStr(Date d, String format){
        SimpleDateFormat sdf = new SimpleDateFormat(format);
        return sdf.format(d);
    }

    public static String firstDateInWeek(Date date){
        Calendar cal = Calendar.getInstance();
        cal.setTime(date);
        int i = cal.get(Calendar.DAY_OF_WEEK);
        cal.add(Calendar.DATE, -1 * (i - 2));
        String firstDate = dateToStr(cal.getTime(), "yyyy-MM-dd");
        return firstDate;
    }

    public static String currentTime(){
        return dateToStr(new Date(), "yyyy-MM-dd HH:mm:ss");
    }

    public static void main(String[] args){
        firstDateInWeek(new Date());
    }

}
